Effects of Al Content on Microstructure and Tensile Properties of Ni-Based Ods Superalloys

Abstract

Two kinds of Ni-based oxide dispersion strengthening (ODS) superalloys with high/low Al contents, ODS-HA (Ni-20Cr-4.5Al-0.5Ti-0.6Y2O3-0.6Zr, wt.%) and ODS-LA (Ni-20Cr-0.3Al-0.5Ti-0.6Y2O3-0.6Zr), were manufactured by mechanical alloying and hot isostatic pressing to investigate the effects of Al content on microstructure and tensile property. The results showed that ODS-HA is strengthened by both γ′ phases and nanoscale oxides together refined grain size, and ODS-LA is strengthened mainly by nanoscale oxides. Type and size of nanoscale oxides depend on Al content. Y4Zr3O12, Y2TiO5, monoclinic Y4Al2O9 (YAM), hexagonal YAlO3 (YAH) and YAlO3 perovskite (YAP) are observed in ODS-LA while only Y4Zr3O12 and YAP are found in ODS-HA. This causes the change of size and number density of oxides in two kinds of ODS alloys. High Al content results in increasing tensile strength and decreasing ductility.

Keywords: Ni-based ODS superalloy, Nanoscale oxides, γ′ phases, Al content, Tensile property.